Suspension adjustment - rebound damping

[Kev m]

My V7 (Guzzi content) is wearing a slightly used set of YSS shocks that I've never quite fully dialed in. They're pretty close, but I tend to get a little too much bounce over repeatedly irregular surfaces.

I might need to play with preload a tad, but for the sake of discussion, would someone who understands this better please help translate the YSS instructions and/or advise me about rebound damping adjustments.

YSS says:

The rebound dampening is adjusted through 60 clicks (You can feel and hear them). The maximum rebound dampening is reached by turning the wheel to the right. So, if you turn the wheel to the left, you are slowing the rebound.

What is the effect of maximum rebound damping. I would have expected that meant it would slow the return of the suspension to the normal, uncompressed position.

But that seams to be the opposite of these instructions.

If the rear suspension is occasionally a little bouncy, mostly comfortable, but relatively firm, would you think I need MORE (turn to right) or LESS (turn to left) rebound damping.

Your patience and any help is appreciated.

[oldbike54]

 Something got lost in translation . You are correctly understanding rebound damping , increasing it should slow down the rate of rebound . Where are YSS products made ?

  Dusty

[Kev m]

Yeah, hopefully something got lost in translation. 

[Peter from Sch'dy]

Just a guess here, try making a gross change, like 20 clicks and see where that goes. small changes are harder to feel. set your sag too.
Best,
Peter

[Kentktk]

Dave Moss is excellent at explaining suspension settings. He has numerous videos. Here is one to get you pointed in the right direction.
https://www.youtube.com/watch?v=Ikjw4IheeF4

[Kev m]

Kirby, what would you recommend about a rhythmic slow bounce over a series of equally spaced expansion joints maybe every 10' or 20'?

More or less rebound dampening... I was thinking more?

[Penderic]

I have a YSS set with the instructions, Kev and the rebound damping adjustment at the base is adjusted such:

Turning the knob at the base of the shock to the LEFT to REDUCE the rebound damping.

I would imagine that as viewed from a normal standing position looking down at the shock as a CLOCKWISE adjustment to REDUCE the rebound damping.

(I could scan and post my YSS booklet page showing those instructions if you wish).

[leafman60]

Kirby, what would you recommend about a rhythmic slow bounce over a series of equally spaced expansion joints maybe every 10' or 20'?

More or less rebound dampening... I was thinking more?

If you are having a pogo type bounce over some regular bumps, try increasing the rebound to settle the suspension.  Likewise, in curves, if you feel the machine wobbling a bit, increased rebound can settle the rear end and keep the shocks from bouncing up and down so much.

As already mentioned, too much rebound will result in a harsh suspension since the shocks cannot rebound and ready themselves for the next bump impact, they pack down.  Offroad, you can actually feel the rear end drop down over a series of sharp bumps. In those situations, lessen the rebound.

Rebound dampening, compression dampening and spring preload all work together and affect each other.  Complicating matters further, suspension settings for one situation are not always best for another.  You must to reach a happy compromise that covers most situations.

On the V7, PYoung has experimented a great deal with suspension upgrades that he says are much needed.

Paul Thede of Race Tech authored what many consider the bible of motorcycle suspension.

http://www.amazon.com/dp/0760331405/?tag=mh0b-20&hvadid=3481101149&hvqmt=p&hvbmt=bp&hvdev=c&ref=pd_sl_6frbuc500j_p

[Kentktk]

On any suspension, turning adjuster knobs or screws in (clockwise) increases damping forces. It`s not really rocket science.

[kirby1923]

Kirby, what would you recommend about a rhythmic slow bounce over a series of equally spaced expansion joints maybe every 10' or 20'?

More or less rebound dampening... I was thinking more?

Getting into the science of suspension tuning is complicated and a little black magic so if I had what you describe I would defiantly increase the damping a small amount at a time until it feels better.
One thing I might add is to try and used the same surface that you feel the bounce or find one that does and use it for the changes 'cause it makes the changes more  identifiable.
I have adjustable on both ends and really the rebound is the only one that is pretty important to our type of riding. Its fun to experiment with it until it "feels" right.

Once dialed in those long sweepers will feel much better.

Edit: One other thing is that with time the dampening will change so you will have to change to keep it where you like it until it goes away.

[oldbike54]

 So Kirbster , gravity pushes down , correct ? GMT +- ?

  Dusty

[Penderic]

The trouble with testing on railroad tracks is that they are not wet enough.

That's better!

[kirby1923]

Yeah, Newton got it wrong, imagine that!

+5 just off duty.

[Kev m]

So to summarize, a few turns to the right, then try again.

Thanks much all!

Very appreciated.

[oldbike54]

So to summarize, a few turns to the right, then try again.

Thanks much all!

Very appreciated.

 Sure , why not   

  Dusty

[Kev m]

Ok, let me try this again.

A few more turns to the right should increase rebound damping (I see I was using the wrong term, dampening meaning to wet). That should slow the return of the wheel after the suspension is compressed. So it basically fights the force of the compressed spring.

But if I'm bouncing because the wheel isn't dropping back in time, then I have too much damping and need to turn it to the left so the wheel can drop into place faster.

But how do I determine that's why I'm bouncing? Trial and error?

If this sounds correct, follow-up question, when you increase preload you generally should also increase rebound damping? Because rebound damping fights the force of the spring which increases as it is compressed. Yes?

[oldbike54]

 Theoretically preload should not affect damping rates .

  Dusty

[kirby1923]

Dampening controls the speed at which the wheel (suspension) moves , and although spring rate figures in the shock manufacturer has all that worked out on a premium shock (as well as compression dampening) so sets the dampening rate at a known (tested) average, but then lets the user fine tune.

Don't over think it!! (I do that allot).

If its bouncy you need to slow the speed by increasing the dampening. Don't worry where the preload is set. Use preload setting just for sag. Preload will not change its (spring) rate.

Welcome to the practical art of fine tuning for the average? street rider. (not calling anyone average!)

Fun no?

[Arizona Wayne]

Get air shocks and none of this will even be felt. 

[Penderic]

Boing Boing - Is there a easy way to measure a springs rate?

I have the optional chrome shrouds on my YSS shocks (I forgot to mention earlier that they are not the model with the remote reservoir - they look more like the stocker shocks).

But I had a problem with my YSS springs under the shrouds. The shrouds were a little small for the spring diameter - not enough clearance, and after a few years some serious rust formed inside the shrouds and the springs started to bind inside the shroud. Oh oh.

I couldn't see that rust until I took the shocks apart in order to paint the springs gloss black. I had to use a lot of force to get them out!

The painted YSS springs wouldn't work with the nicer original stock shrouds that I planned to reuse, so I had to go back to the stock springs on the YSS shock body. Works pretty good. I think it is a stronger spring.

I should have measured the spring rates of the different shocks for any future decisions.  doh!

[redrider]

Gostar racing web page details the set-up. Follow the instructions and you will be amazed at the feel and precision.

[Kev m]

Feel free to call me average, especially around some of the riders I've met through WG. 

For the record I asked about preload and any relationship to damping because Stormtruck might be borrowing the V7 today and he's got me by a good 50# at least. I figure I'm going to have to adjust the shock for him and then adjust it back again when I get it back.

I'll note changes from the current settings, but I wanted a starting point for what I was going to do to set it up for him.

[Mike Tashjian]

I measure unknown spring rates with a hydraulic press and a trailer scale.  I compress the spring and see how much the scale deflects for every inch of compression.  The spring must must be captured during the testing as they have enough force to seriously injure you if they get loose while compressed.  Safety first when dealing with springs.  Mike